JPS6088931A - Photometry device of camera - Google Patents

Abstract

PURPOSE:To correct the variation in photometric value in a camera which meters light in the rear by a superimposing display method by making a shift in photometric level on transition from superimposing display to another display method. CONSTITUTION:The indication of a lens rotating direction and the focusing state right after an in-focus state is entered are displayed on a liquid-crystal display plate 7, and a photodetecting element 11 for light metering is arranged behind it. Therefore, when focusing display on superimposing basis disappears after the in-focus state is entered and an LED3c outside a viewfinder visual field is turned on for the display, photodetecting element varies in illuminance and the photometric value varies abruptly. Then even when a counterclockwise rotation indication mark turns on and the quantity of light decreases, a light metering lens is corrected. Thus, the photographic level is shifted when the superimposing display is switched to the other display to eliminate a flicker of exposure value display without any variation in photometric value before and after the display transition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photometry device for a camera, which has a photometry circuit that measures the brightness of a subject and a display mark that indicates the focus position of the subject within the viewfinder field of view.

Conventionally, the display mark of such a camera is generally placed outside the viewfinder field of view to indicate the lens rotation direction and focus so as not to overlap the subject image within the viewfinder field of view. Because of this inconvenience, a so-called superimpose display device has recently been proposed, which displays a display superimposed on the subject image within the viewfinder field of the camera. This is a liquid crystal panel with a lens rotation direction indicating mark placed near the focusing plate near the focusing area so that the distance ring of the lens can be operated according to the output of the focus detection device while looking at the image of the focusing area within the viewfinder field of view. This is displayed by the superimpose display means, and when the in-focus state is reached, this is displayed by the suit 9-impose display means. However, in the focused state, the display of the focused state superimposed on the subject image within the field of view of the finder becomes a hindrance to photographing. In order to solve this inconvenience, the applicant has proposed that after reaching the in-focus state,
We have developed a display device that immediately or after a predetermined period of time turns off the suit 9-impose display and displays focus using another display means outside the viewfinder field of view. According to this device, it is possible to easily focus according to the lens rotation direction indication mark on the superimpose display, and when the focus is reached, it is first displayed in superimpose so that the camera can actively take pictures. can be conveyed to. Furthermore, immediately after the in-focus state is reached or after a predetermined period of time, the in-focus display shifts from superimposition to another display means, so that it does not interfere with photographing.

However, when using a suit or a type of camera that measures light at the rear of the superimposed display, such as a single-lens reflex camera, the superimpose display disappears and the superimpose display is switched to another display means outside the viewfinder field of view. There is a drawback that when the light is turned on, the illuminance on the light receiving element changes and the photometric value suddenly changes.

An object of the present invention is to correct changes in photometric values when transitioning from superimposed display to other display means in a camera of the type that performs photometry behind the superimposed display means as described above. It is something to do.

The camera according to the invention includes a photometering circuit that measures the brightness of a subject, a display IU path that allows a display mark to be turned on and off to indicate the image formation state of the subject within the viewfinder field of view, and a display mark that indicates the lighting state and turning off of the display mark. The apparatus further includes means for outputting a correction signal to the photometry circuit based on the output signal of the display circuit of the state.

Hereinafter, the present invention will be described in detail with reference to the drawings. ◇Figures 1 to 8 show examples of implementing the present invention. Figure 1 is an explanatory diagram of the optical system of the display device in the finder. In the figure, 5 is a 45° mirror that guides the light beam after passing through the photographic lens to the finder optical system, 6 is a focusing plate, and 7 is a rotating lens in the finder. Includes a GH phase transition type liquid crystal display panel to display direction indication marks. 8 is a condenser lens, 9 is a Bentapha prism, IO is a photometric lens for projecting an image on a focusing plate onto a light receiving element, and 11 is a light receiving element.

Further, 3c is an LED for indicating focus.

Figures 2 to 6 are explanatory diagrams of the display in the finder of the above device, in which 1 is the viewfinder field of view, 2 is the distance measurement area indicating the range of the image used for focus detection, 3a and 3
b is a lens rotation direction indicating mark that indicates the direction in which the distance ring of the lens should be rotated according to the output of the focus detection device. This is the viewfinder view IJT as shown in the diagram.
The direction of rotation of the lens is indicated when the superimposed display is turned on, and is displayed on the liquid crystal display board 7 disposed on the optical path near the focusing plate 6. The focus display LED 3c is located outside the viewfinder field of view l, and lights up immediately or after a predetermined time after reaching the focus state to indicate the focus state. In the figure, 4 indicates the photometric range.

Hereinafter, display modes by the above-mentioned display device will be sequentially explained.

Fig. 2 shows an operating state in which only the indicator mark 3a lights up to indicate an instruction to rotate the photographing lens distance ring to the left. Fig. 3 shows an operating state in which only the indicator mark 3b lights up to indicate an instruction to rotate the photographing lens to the left (only 3b is displayed). It is. Both FIGS. 4 and 5 show the in-focus state, and FIG. 4 shows the operating state in which both the indicator marks 3a and 3b catch the fish immediately after the in-focus state is achieved, and the in-focus state is indicated. Figure 5 shows an operating state in which the indicator marks 3i and 3b% are turned off after a predetermined time has elapsed after focusing, and 3e% (lit.
There has been a shift from focus indicators using suits or single-impose indicators to LED indicators outside the viewfinder field of view. FIG. 6 shows an operating state in which the focus detection device cannot determine the direction, and the indicator marks 3a, 3b and LED 3c are all off. The outlines of the lens rotation direction indication marks 3a and 3b shown in FIGS. 2 to 6 are drawn for explanation purposes only, and cannot be seen if they are not actually displayed.

In the camera shown in FIG. 1, instructions for the direction of rotation of the lens and a focus display immediately after the in-focus state is reached are displayed on a liquid crystal display board 7, and a light-receiving element 11 for photometry is arranged behind this display means. has been done. Therefore, if after reaching the in-focus state, the in-focus display by the so-/y-impose disappears and shifts to the display by the LED 3c outside the viewfinder field of view, the illuminance on the light receiving element changes and the side light The value changes suddenly.

According to the present invention, means for correcting such changes in photometric level is provided. Below, we will explain how to correct the photometric value when switching from such a suit-imposed focus display to an IJD display outside the viewfinder field of view.
This will be explained with reference to FIGS. 1 and 7.

The image on the focusing plate is projected by the photometric lens 10 onto the light-receiving element 11, and the lens rotation direction indicating mark is also substantially focused thereon. Therefore, a clear photometric range is shown on the focusing plate, and this is 4 shown in FIGS. 2 to 7.

The area of the part within the photometric range of lens rotation direction indication mark 3a' (rss, similarly, the surface π1t of the part within the photometry range of 3b = Sz, the area within the photometry range other than lens rotation direction indication marks 3a and 3b) The area of the part is 83. Also, the average transmittance of visible light when the lens rotation direction indication mark 3a or 3b is displayed and the light absorption state is α0, and conversely, when the display of 3a or 3b is turned off and the light is transmitted In this state, the average transmittance of visible light in a portion other than the lens rotation direction indication mark is αl.

When the incident light flux to the side light range 4 is φ, the following relationship holds between the light flux V after passing through the focusing plate 6 and the liquid crystal display plate. (1) When the lens rotation direction indicator mark is turned off (the fifth Figure) 11
-α, φ (2) When only the lens rotation direction indication mark 3a is lit (Fig. 2) (3) When only the lens rotation direction indication mark 3b is lit (4) When the lens rotation direction indication mark 3a is lit , 3b are both lit S H = 20+nm2, S 2 = 20mm2, S
3 = 40mm2α. = 0.4 and αl = 0.7 and make a prototype, φll 1φ'2 and φ'3+la will be as follows.

φ'1=0.7φ, g2=o, 625φ, g3=0.6
25 φ, ta, = 0.55 φ Therefore, in the state (4), the transmitted light flux is about 0.786 times as large as that in the state (1). When converted to total exposure value, this is a decrease of 0.35 Ev. That is, there is a difference of 0.35 EvO between the photometric value in the state (1) and the photometric value in the state (4). When transitioning from the superimposed focus display (Figure 4) to the LED display outside the viewfinder field of view (Figure 5), the pointer of a camera with a meter display will swing by an equal amount of 0.35 Ev. Furthermore, in a camera that uses digital display in increments of 0.5 Ev, the display may change by 0.5 Ev.

In the embodiment described above, the focus display is shifted to the IJD display outside the viewfinder field of view after a predetermined time from the suit 4-impose, but it may be shifted to a sound display. Figure 8 shows
This is an explanatory diagram of a camera incorporating such a sounding body.
2 is a camera body, and 13 is a sounding body. In this case as well, the photometry level needs to be corrected.

FIG. 9 shows an embodiment of a camera operating circuit including a display device that shifts the focus display from the suit-impose display to the IJD display outside the viewfinder field of view as described above.

In FIG. 9, ■ indicates a circuit of a suit or one-imposed display device, and ■ indicates a photometry and photometry value correction circuit. In circuit 1, S is the display section in the viewfinder, R and L
is an input terminal for a lens rotation direction instruction signal obtained from an autofocus circuit (not shown), R is a signal source for indicating clockwise rotation, and L is a signal source for indicating counterclockwise rotation. RlgM, Left,
Those indicated as Common are input terminals of each LCD display of the display section S, and Dl is an LED for indicating focus. A1 to A8 are ANDr-), NAI to NA5 are Nando darts, inl to in5 are inverters, DFL
is D flip frog, cTl is counter, R1-R
2 is a resistor, cl is a capacitor, EOI, EO2 is an exhaustive OR dart, and the one marked CK is a suitable lock (for example, 32 kHz).

Rl p C1, in4 is a circuit for initializing when the power is turned on. A combination of the time constants of R1 and CI and the threshold level of in4 produces one pulse of IH1'' to reset the latch constituted by NA3 and 4. The output of NA3 becomes L''. If the image is in focus in this state, both R and L will be 1H''', j), and the output of AI will be 'H'. One shot of 'H' is output from A2, and CT1 is reset and starts counting an appropriate time from the beginning.At the same time, NA3.4 is latch-reset.

After a certain period of time, the output Q of CTI becomes "H", the output of NA5 becomes @L" and the latch is inverted, the output of NA3 latches "H", and the output of A5 becomes "H". jjJDl
That is, the LED lights up. At the same time, ins becomes -L" and A6 becomes 'L', and the outputs of A7 and A8 are 1L"
Then, the Rlght and Left terminals are in the same phase as the Common, and the LCD turns off.@Next, if the R signal is “H” and the L signal is @L, A1 becomes 1.
# Tonashi NA5 is “H”, A4 is H# and NA3 # 4
latches remain reset.

Therefore, A5 is 1L'' and Dl is off.

Also, since A7 becomes ``H'' and 88 becomes @L, Rlght is in the opposite phase to common, and since Left is in the same phase, only Right is lit. This is because R and L are reversed, so please refer to this.

Next, circuit (2) of the photometry and photometry value correction device will be explained. In the figure, vc is an appropriate voltage, and icv is τ.

The voltage obtained by multiplying by (K>1) is shown. OPI～O
P6 is an operational amplifier, R3-R9 are resistors, M1-M2 are M
OS) is a transistor. MOS) transistor Ml
, M2 is connected to A7#A8 of circuit I,
It turns ON when terminals R and L become H#. D2*DB is a diode, C2 is a capacitor, Trl is a transistor, and PD is a light receiving element corresponding to that shown by 11 in FIG. Δ is a photometric calculation circuit that digitally calculates the photometric value based on the output of the above-mentioned operational amplifier OP6, Δ is an operation control circuit that controls the shutter aperture, etc. based on the calculation result of the photometry calculation circuit, and Δ is the output of the operational amplifier OP6. Operational amplifiers OP3 and OF2 are activated at appropriate timing.
e This is a photometry control circuit that turns ON and OFF.

In the above circuit, the counterclockwise rotation instruction mark 3 in the display section S
Assume that the amount of light hitting the light receiving element PD is reduced due to the addition of a. Due to this decrease in the amount of light, the output of O20 decreases by that amount, and accordingly, the output of O20 increases. However, M2 connected to A8 turned on and 8
5 and M2 to the inverting input side of O20, and the output of O20 is controlled in the downward direction.

Here, the current flowing through RI e as l R7 is defined as Zi
Set pi1+j3 and set the output voltage of O20 and O20 to VOP
2, VQP3, and the light amount change is A times (
Assuming that a change of 0<A<1) has occurred, the counterclockwise rotation instruction mark 3
O20 after a lights up, O20 output k V'opa
' ``O20.In order to distinguish the current when lighting, the current after lighting is indicated with a dash.

Here, calculate the value of R5 for photometric value correction.

The equation before lighting is The equation after lighting is Substituting ■■■■■ into becomes.

Now the counterclockwise rotation instruction mark lights up, and even if the light intensity decreases,
It can be corrected. The same applies when a clockwise rotation instruction mark is attached. If both are on, Ml and M2 turn on and 21!
flows into the OP3 inverting input terminal as a correction current.The photometry level is corrected as described above.

FIG. 11 shows a circuit of the display device when the display device 9 shifts to LED lighting after focusing and then shifts to sound generation as shown in FIG. 8. CTl0 is counter AI0.11 is andf
-) A5 is the same dart as A5 in Figure 9. DF
IO is a D type 7 Ritsu flop R8° is a protective resistor B is a buzzer such as a piezoelectric element.

The operation of this circuit will be explained. At the moment when A5 becomes 'H', 'H' is output from the one-shot circuit composed of DFIO and All, and immediately becomes 'L'.
Tl0 is reset to 4 kHz and 4 Hz.

1H AND is output from AIO and drives B. AI
The output waveform of O is shown in FIG.

In this case as well, the photometry level is corrected in the same way as above.

As explained above, according to the present invention, in a camera equipped with a focus detection device that is configured to shift from superimpose display to another display means immediately or after a predetermined time after focusing, superimpose display is possible. By shifting the photometric level at the time of switching from display to other display means, the following effects can be obtained: (1) The photometric value does not change before and after the display transition.

(2) Flickering in the exposure value display is eliminated.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the optical system of the display device in the viewfinder in an embodiment of a camera equipped with a photometric device according to the present invention;
2 to 7 are explanatory views of the display in the display device shown in FIG. 1, FIG. 8 is a front view showing another embodiment of the camera equipped with the photometric device according to the present invention, and FIG. 10 is a circuit diagram showing the circuit in the embodiment shown in FIG. 8, and FIG. 11 is a diagram showing the output waveform of the circuit shown in FIG. 10. 1...Finder field frame 2...Distance measurement area 3
a + 3 b... Lens rotation direction indication mark 3c.
...Focus display LED 4...Metering range 5...45
° Mirror 6... Focusing board 7... Liquid crystal display board 8.
...Condenser lens 9...Penta roof prism
10... Photometric lens 11... Light receiving element 12...
Camera body 13... Pronunciation body 1) Positive line, ', 1 11? -1, I Fig. 1 Fig. 3 Fig. 5 Fig. 6 Fig. 8 Procedure t111 official text 1. Indication of elementary school 1, relationship with subject matter Applicant 4, junior J! lt person 1jIsu1 Tojito "21-1 Marunouchi, 1st ward] 6
No. 2 No. 9 Uchizume Φzu Building 3301 - Correction The following items in the main stable drawing will be corrected. Note 1, Figure 1 in the drawing, Figure 9 will be corrected to the drawing submitted today.

Claims (1)

[Claims] A photometric circuit that measures the brightness of a subject, a display circuit that enables all display marks to be turned on and off to indicate the imaging state of the subject within the viewfinder field of view, and an output signal of the display circuit that indicates the lighting and off states of the display marks. 1. A photometric device for a camera, comprising means for outputting a correction signal to said photometric circuit based on said photometric circuit.